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Chapter: LSS (Location
Specific Services) and mDNS AP

LSS (Location Specific Services) and mDNS AP

In release 7.5 additional Bonjour
enhancements were added on the WLC. One of them is processing of mDNS service
advertisements to support LSS. Basically all valid mDNS service advertisements
received at the WLC will be tagged with the MAC address of the AP associated
with the service advertisement from the Service Provider device, so in essence
only clients connected to the same AP as the SP will have access to that service.
LSS only applies to wireless SP-DB entries. There is no location awareness for
wired SP devices.

To summarize,

LSS filtering applies only
to wireless SP-DB entries.

Wireless SP-DB entries are
filtered based on the AP-NEIGHBOR-LIST if LSS is enabled for the service.

Only client in the same “RF
neighborhood” as the service provider will be granted permission to use that
service

The location of clients and service providers is established by the MAC
address of their associated AP's. The RRM DB provides the list of neighboring
AP for any given AP and this information will be acted upon while filtering the
SP-DB wireless entries in response to mDNS queries originating from wireless
clients.

For Wired clients / service providers there is no sense of location
that could be applied similarly and so the wired SP-DB entries cannot be
filtered similarly.

Below is the network diagram of LSS enabled Bonjour gateway.

When the client query for the service the WLC using the client AP MAC
address look up the RRM DB for the neighbor AP-list and filter the SP-DB for
the service with the service provider's associate with the AP-list while
responding to the query.

mDNS AP

Bonjour mDNS as mentioned earlier,
is a link local multicast and thus forwarded on Local L2 domain. Therefore mDNS
services behind the Router or not L2 adjacent will not be seen by WLC in
release 7.4 as illustrated below.

In release 7.5 the mDNS AP was added as enhancement and to correct the
mDNS L2 limitations. mDNS AP has the ability to snoop wired Services on VLANs
invisible to WLC

This enhancement allows the controller
to have the visibility of wired service providers, which are on VLANs that are
not visible to the controller.

VLAN visibility at the WLC
is achieved by APs forwarding the mDNS advertisements to the controller.